生成随机DAG [英] Generating a random DAG

问题描述

我正在解决有向无环图上的问题。

I am solving a problem on directed acyclic graph.

但是我在一些有向无环图上测试代码时遇到了麻烦。测试图应该很大，并且（显然）是非循环的。

But I am having trouble testing my code on some directed acyclic graphs. The test graphs should be large, and (obviously) acyclic.

我尝试了很多代码来生成非循环有向图。但是我每次都失败了。

I tried a lot to write code for generating acyclic directed graphs. But I failed every time.

是否有一些现有方法可以生成我可以使用的无环有向图？

Is there some existing method to generate acyclic directed graphs I could use?

推荐答案

我编写了一个执行此操作的C程序。关键是对节点进行排名，并且仅 会将边缘从排名较低的节点绘制到边缘较高的节点。

I cooked up a C program that does this. The key is to 'rank' the nodes, and only draw edges from lower ranked nodes to higher ranked ones.

我编写的程序可以打印在 DOT语言中。

The program I wrote prints in the DOT language.

此处是代码本身，并带有注释，解释其含义：

Here is the code itself, with comments explaining what it means:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define MIN_PER_RANK 1 /* Nodes/Rank: How 'fat' the DAG should be.  */
#define MAX_PER_RANK 5
#define MIN_RANKS 3    /* Ranks: How 'tall' the DAG should be.  */
#define MAX_RANKS 5
#define PERCENT 30     /* Chance of having an Edge.  */

int main (void)
{
  int i, j, k,nodes = 0;
  srand (time (NULL));

  int ranks = MIN_RANKS
              + (rand () % (MAX_RANKS - MIN_RANKS + 1));

  printf ("digraph {\n");
  for (i = 0; i < ranks; i++)
    {
      /* New nodes of 'higher' rank than all nodes generated till now.  */
      int new_nodes = MIN_PER_RANK
                      + (rand () % (MAX_PER_RANK - MIN_PER_RANK + 1));

      /* Edges from old nodes ('nodes') to new ones ('new_nodes').  */
      for (j = 0; j < nodes; j++)
        for (k = 0; k < new_nodes; k++)
          if ( (rand () % 100) < PERCENT)
            printf ("  %d -> %d;\n", j, k + nodes); /* An Edge.  */

      nodes += new_nodes; /* Accumulate into old node set.  */
    }
  printf ("}\n");
  return 0;
}

这是从测试运行生成的图形：

And here is the graph generated from a test run:

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